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Name: Whittier College
Organic Chemistry: CHEM 231A
Test # 4
120 Points Total November 24, 2003
- Concisely answer the following questions: (24 points = 6 pts each)
1a. What is a conformational isomer? Provide two structures that are conformational isomers and explain their relationship.
1b. What is an organometallic reagent? Provide an example and use this example to explain its reactivity.
1c. What kind of reaction do organic chemists consider to be an oxidation reaction? Provide an example and explain briefly.
1d. What is the 3-D shape of a cyclohexane? Why is it this shape?
- Consider the following reactions. Predict the single MAJOR product and briefly explain your answer. Mechanisms are NOT required, but may be used: (24 points – 8 points for each)
2a.
2b.
Na 2 Cr 2 O 7
H 2 SO 4 / H 2 O?
OH
O
Cl
OH
Mg / Et 2 O
Aqueous Work-up
O H
2c.
O
O O
H (^) Li
O (THF)
- Provide the two most stable 3-D representations for the following molecules and briefly explain your rationale. (12 points = 2 pts each)
Br
5a.
5b.
- Consider and explain thoroughly the following set of experiments: (25 points)
Compound A
OH CF 3 SO 2 Cl / Pyridine (^) Compound B potassium t-butoxide DMF
Compound C
Compound D
OH CF 3 SO 2 Cl / Pyridine (^) Compound E potassium t-butoxide DMF
Compound F
Rate = 155 minutes
Rate = 5 minutes
5a. What is the structure for compound C? (2 points)
5b. What is the structure for compound F? (2 points)
5c. Explain why the rate for the two reactions are so different. Use energy diagrams to help answer the question. (7 points)
5d. If compound A or D are heated in the presence of 1M H 2 SO 4 , then two new major products (compounds G & H) are formed with the molecular formula C 10 H 20 O. These two molecules have very similar NMR spectra and very similar Rf values of each other; however, G & H are fairly different than compounds A or D. What are the structures of compounds G & H? (4 points)
5e. Choose one of the conversions and show a mechanism that accounts for the formation of either compound G or H from either compound A or D under 1M H 2 SO 4 reaction conditions. (8 points)
5f. Would you expect G & H to be the only products? Explain very briefly. (2 points)
